Metal foil, for example copper foil, is often laminated to a dielectric substrate. Resultant laminates are subjected to numerous processing techniques as well as inevitable wear and tear. In this connection, it is desirable to provide a laminate having high peel strength. High peel strength enables a laminate to maintain its structural integrity during processing (exposure to chemicals and various etchants, such as hydrochloric acid) and over the course of normal wear and tear (heat degradation, physical agitation, and so forth).
Metal foils are typically treated to increase surface roughness and thereby increase the peel strength of resultant laminates. However, metal foils having increasingly high levels of surface roughness are subject to "treatment transfer", which is the undesirable migration of metal material from the metal foil to the dielectric substrate. Treatment transfer lowers the peel strength as well as degrading the insulating properties of the dielectric substrate. Treatment transfer also leads to unsightly yellow staining after the metal foil is etched. Accordingly, it is desirable to provide metal foil which not only exhibits high peel strength when incorporated into a laminate, but also does not affect the insulating properties of the dielectric substrate.
When metal foils are treated to increase surface roughness, an electrolytic process is typically utilized. For example, a nodular or dendritic layer of copper or zinc is electrodeposited on metal foil to increase the surface roughness. This process is not only time consuming, but also expensive because of the enormous amount of electricity needed to applying a nodular layer of copper or zinc. Accordingly, it is desirable to increase the efficiency and cost-effectiveness of treating metal foils.